Up until this time various arrangements have been known for removing residues from conveyors belts, including for example scrapers mounted in such a way as to be held in contact with the moving surface of a conveyor belt, the scrapers being used to remove residues from the belt. Such an arrangement for cleaning conveyor belts is known from Australian patent specification No. 449,142. While such arrangements have met with some amount of commercial success, they have not been as successful as might have been expected, given that there has been limitation to the amount of matter that can be removed from the belt. In particular, the scrapers have not always been effective since they do not always faithfully follow the contours of the belt. Furthermore, such scrapers alone are not always effective for all cleaning requirements. For example, a sticky substance adhered to the belt is generally unable to be removed from the belt by a scraper alone or if it is removed, then it often adheres to the scraper, thus reducing the efficiency of the scraper. Further, it has been found that the build-up of residues and molds on conveyor belts is indicative of the disadvantages of relying on scraping means alone to clean conveyor belts.
It has also been found that many particles of substances adhering to or being built-up on the surface of a conveyor belt, are of a profile sufficiently flat to pass under a scraper without being dislodged from the belt. This problem has been aggravated by the fact that with flat, compressed particles, there may well be no space for a layer of air between the belt and particle, as a consequence of which flat particles are often held tightly on conveyor belts by air pressure or suction.